Self-adjusting valve tappets



5 w v 0 E M 2 m a m M r/ "99 n 7 4 w J a 7 Jan 28, 1958 J. M. REKOW SELF-ADJUSTING VALVE TAPPETS Filed NOV. 29,- 1955 I a I United States Patent SELF-ADJUSTING VALVE TAPPETS Joseph M. Rekow, San Francisco, Calif.

Application November 29, 1955, Serial No. 549,707

Claims. (Cl. 123-90) This invention relates to new and useful improvements and structural refinements in valve tappets of internal combustion engines, and the principal object of the invention is to provide a tappet mechanism which is fully self-adjusting as to clearance while the engine is in operation, thus eliminating the noise and other incident disadvantages which commonly arise when conventional tappets, manually adjusted as to clearance, lose their proper adjustment.

Some of the advantages of the invention reside in its simple construction, efficient operation, and in its adaptability to embodiment in valve systems of various types.

With the foregoing more important objects and features in view and such other objects and features as may become apparent as this specification proceeds, the invention resides in the details of construction and arrangement of parts substantially as shown in the accompanying drawing, wherein like characters of reference are employed to designate like parts and wherein:

Figure 1 is an elevational view, partly in section, showing a valve actuating mechanism embodying the invention;

Figure 2 is a fragmentary vertical sectional view of the rocker arm having the invention embodied therein;

Figure 3 is a fragmentary top plan view of the same;

Figure 4 is a plan view of the top spring and its supporting plate used in the invention;

Figure 5 is a plan view of the bottom spring and its supporting plate;

Figure 6 is a side elevational view of the adjusting shaft;

Figure 7 is a fragmentary perspective view showing the connection of the keeper plate to the rocker arm body; and

Figure 8 is a cross-sectional detail, taken substantially in the plane of the line 8-8 in Figure 2.

Referring now to the accompanying drawing in detail, the reference numeral 10 designates a conventional overhead valve actuated by a rocker arm 11 upon a rocker arm shaft 12 by a push rod 13 which, in turn, is operated by a cam 14 driven by the associated engine.

In accordance with the invention the rocker arm 11 is provided at the push rod side thereof with a vertically extending, substantially cylindrical body 15, which affords therein a chamber 16 having its lower end portion internally screw-threaded as indicated at 17.

An externally screw-threaded adjusting sleeve 18 rotatably engages the screw threads 17 in the chamber 16, the thread of the body preferably having a lead of approximately .200" over the thread of the sleeve, for a purpose hereinafter described.

The sleeve 18 is provided with an axial bore 19 having a frusto-conical counterbore 20 at its lower end and also having a pair of cam tracks 21 on diametrically opposite sides thereof. An adjusting shaft 22 is slidable and rotatable in the bore 19 and is provided at its lower end with a frusto-conical base 23, disposed in the recess or counterbore 20 of the sleeve 18. The shaft 22 is also ice provided adjacent the base 23 with a diametrically projecting cam follower element such as a pin 24. The end portions of this pin are disposed in the cam tracks 21 and consequently, if the shaft 22 is slid axially in the bore 19 relative to the sleeve 18, it will be also sub jected to simultaneous, partial rotation in the bore.

The base 23 is provided at the underside thereof with a convex portion 23a disposed in a concave seat 25 at the upper end of the push rod 13, as will be clearly apparent. The base is also formed with a plurality of suitable oil passages 26 extending to the frusto-conical surfaces at the counterbore 20.

The top of the sleeve 18 is provided with a relatively shallow counterbore 27 to receive the bottom portion of a stop collar 28 which is secured to the shaft 22 by a transverse pin 29. The parts are so arranged that when the shaft 22 is slid downwardly relative to the sleeve 18, a predetermined amount of clearance exists between the frusto-conical surface of the base 23 and the frustoconical surface of the counterbore 20, as indicated at 30. On the other hand, when the shaft is slid upwardly relative to the sleeve, the same amount of clearance exists between the collar 28 and the top face of the sleeve in the counterbore 27.

Resilient means are provided for rotationally urging the sleeve 18 in a counter-clockwise direction relative to the shaft 22, these means comprising a bottom spring 31, configurated as shown in Figure 5, and having looped ends anchored to a pair of upstanding pins 32 which, in turn, are secured to and project through a bottom spring supporting plate 33 rotatably positioned on the shaft 22 immediately above the collar 28.

The upper portion of the shaft 22 is formed with a transverse slot 34 open at its upper end, and the intermediate portion 31a of the spring 31 is anchored in this slot. The lower end portions of the pins 32 are slidably disposed in suitable bores 35 provided in the top of the sleeve 18, whereby the spring and its supporting plate may move upwardly and downwardly with the shaft 22 relative to the sleeve.

Resilient means are also provided for rotationally urging and tensioning the shaft 22 in a clock-wise direction relative to the body 15, these means comprising a top spring 36, configurated as shown in Figure 4, and having looped ends anchored to a pair of upstanding pins 37. The latter are secured to a top spring supporting plate 38 rotatably positioned on the shaft 22 above the bottom spring 31. The spring 36 has its intermediate portion 36:: also anchored in the slot 34 of the shaft 22. The pins 37 project upwardly through a pair of recesses 39 formed in a combined keeper and tensioning plate 40, the latter being disposed at the top of the chamber 16 and being provided with radially projecting lugs 41 extending through bayonet slots 42 at the top edge of the body 15, as is best illustrated in Figure 7.

Finally, a keeper collar 43 is secured to the shaft 22 by a transverse pin 44 above the top spring 36 and extends loosely into a central opening 45 formed in the plate 40.

Having thus described the construction of the invention, its operation will now be explained.

When the lobe of the cam 14 is at the bottom and the push rod 13 is slid downwardly, the clearance 30 exists between the base 23 of the shaft 22 and the sleeve 13, as shown in Figure 2. As the cam 14 rotates and the push rod 13 slides the shaft 22 upwardly to open the valve 11) through the medium of the rocker arm 11, the clearance will be shifted by the sliding action of the shaft in the bore 19 so that it then exists between the top of the sleeve 18 and the stop collar 28. Simultaneously with its upward sliding movement, the shaft 22 will be rotated through a part revolution by the action of the pin 24 in the cam tracks 21, thus placing tension on the bottom spring 31 inasmuch as the sleeve 18 is held against rotation by the body 15.

As the stem of the valve starts expanding when the push rod 13 travels downwardly again, the clearance be? tween the top of the sleeve 18 and the collar 28 is maintained. However, the sleeve 18 is held against rotation by frictional Contact or drag between the parts 14, 13, 23 and 18 and the lead of the screw-thread 17 will permit the sleeve to turn under the action of the bottom spring 31. This turning action, acting through the cam tracks 21 on the pin 24 of the relatively stationary shaft 22, will cause the sleeve to shift upwardly, with the result that the clearance Will again exist at 30, that is, between the base 23 and the bottom of the sleeve, and clearance between the top of the sleeve and the collar 28 will be eliminated.

When the stem of the valve 10 is normal and clearance exists at 30, the top spring, which is only about one-half as strong as the bottom spring 31, rotatively urges and tensions the entire assembly in the body so that the clearance is maintained at 30. The top spring 36 is pre-adjusted as to tension by simply disengaging the lugs 41 from the slots 42 and rotating the plate 40 as necessary to place the top spring 36 under the desired amount of tension.

It is to be noted that the frusto-conical configuration oi the base 23 and of the recess effectively assures that the shaft 22 and the sleeve 18 are in proper alignment.

In the drawing the invention has been shown as being embodied in the rocker arm of an overhead valve mecha nism. However, the same may also be used in valve tap pets of L-head engines by having the tappet body 15 in operative engagement with the lower end of the valve stem.

While in the foregoing there has been shown and described the preferred embodiment of the invention, various modifications may become apparent to those skilled in the art to which the invention relates. Accordingly, it is not desired to limit the invention to this disclosure and various modifications may be resorted to, such as may lie within the spirit and scope of the appended claims.

What is claimed as new is:

1. In a self-adjusting tappet mechanism, the combination of a body operatively connected to a valve stem and provided with a substantially cylindrical vertical cham- 45 her internally screw-threaded in the lower portion thereof, an externally screw-threaded adjusting sleeve rotatable in the screw-threads of said chamber, said sleeve being provided with an axial bore having a frusto-conical counterbore at its lower end and a cam track in a side thereof,

an justing shaf x nd ng .slisiably and rotatably through said bore, a frusto-conical base provided at the lower end of said shaft and operatively connected to a valve push rod, a stop collar provided on said shaft above said sleeve, a cam follower element provided on said shaft and operatively engaging said cam track whereby the shaft is rotated in said bore simultaneously with sliding thereof relative to the sleeve, said shaft being slidable upon rotation thereof in said bore to provide clearance selectively between said collar and the top of the sleeve and between said base and the frusto-conically recessed underside of the sleeve, a pair of springs anchored to said shaft in said chamber, means operatively connecting one of said springs to said sleeve and further means operatively connecting the other spring to said body, whereby to rotatively urge said shaft to a position wherein clearance exists between said base and the frusto-conicaliy recessed underside of the sleeve.

2. The mechanism as defined in claim 1 wherein said shaft is provided with a slot having said springs anchored therein, said means operatively connecting the first of said springs to said sleeve comprising a support plate rotatably mounted on said shaft, and a pin provided on said plate and having the first spring anchored thereto, said pin being operatively connected to said sleeve.

3. The mechanism as defined in claim 1 wherein said shaft is provided with a slot having said springs anchored therein, said means operatively connecting the second spring to said body comprising a support plate rotatably mounted on said shaft, and a pin provided on said plate and having the second spring anchored thereto, said pin being operatively connected to said body.

4. The mechanism as defined in claim 3 wherein the operative connection between said pin. and said body includes means for varying the tension of said second spring.

5. The mechanism as defined in clairn 1 wherein said body is formed integrally with a rocker arm in operative engagement with said valve stem.

References Cited in the file of this patent UNITED STATES PATENTS 1,452,276 Jerdone Apr. 17, 1923 1,820,891 Spiller Aug. 25, 1931 FOREIGN PATENTS 601,725 Germany Mar. 11, 1933 

